Dim wkbkdestination As Workbook
Dim destsheet As Worksheet
For Each ThisWorkSheet In wkbkorigin.Worksheets
\'this throws subscript out of range if there is not
Some folk dislike this approach because of an "inappropriate" use of error handling, but I think it's considered acceptable in VBA... An alternative approach is to loop though all the sheets until you find a match.
Function WorksheetExists(shtName As String, Optional wb As Workbook) As Boolean
Dim sht As Worksheet
If wb Is Nothing Then Set wb = ThisWorkbook
On Error Resume Next
Set sht = wb.Sheets(shtName)
On Error GoTo 0
WorksheetExists = Not sht Is Nothing
End Function